Re: How should we wire the photoswitchs?
 

i am finding the same problem. i have no idea how to set this up and i have teammates wanting to start toying around with thte code. if any one can help out please do. im not one to toy around and try new connections because last time i did that i kind of blew our camera.

Re: How should we wire the photoswitchs?
 

Hey Amanda, here's how I ended up getting it working:

Take the signal wire from the switch (it's gonna be white or black) and connect it to the white part of a PWM cable, then plug it into the Digital I/O like any other switch.

The brown wire should go to the red opening of the power distribution board.

The blue wire should go to the black opening of the power distribution board.

Put a 20 amp breaker (Might be 30, I'm not sure) in the slot above where you plugged it in, and off you go!

So you know: When the black wire from the switch is connected, it means there'll be a "true" reading when it's on a black surface. It'll turn "false" when it goes onto the surface or another lighter source.

Re: How should we wire the photoswitchs?
 

Liu,
The WAGO terminals really don't do well on small wire. It is best to splice to #18 and use that to insert into the PD. Use a 20 amps please.

Re: How should we wire the photoswitchs?
 

Success !
Runs good.
Thanks in part to Al S. and Tem1514's direct and succinct answers.

I like the simplicity of the 12 supply, but the one problem that we had during our evening of testing turned out to be due to supply voltage drop as the battery went down. For a while we thought that we had broken the sensor.
The unit draws from 11 ma to 50 ma in our tests.
Since we have no plans (yet) for them after autonomous, I've decided to hold off on devising extreme measures to stabilize their supply voltage.

Still toying with a stratagem that says if three's good then five's better.

Re: How should we wire the photoswitchs?
 

Charlie,
Were you using the robot battery or some other 12 volt source? Did you happen to measure the battery when you started to experience problems? Were there any changes in the LEDs on the photoswitch?

Re: How should we wire the photoswitchs?
 

If you don't feel confident in your splicing ability, you can use a section of the BM-M092CS terminal blocks that came in the Kit of Parts instead.

Re: How should we wire the photoswitchs?
 

Since you have three of the sensors in the KOP the easy way to get power to them is by using the BM-M092CS terminal blocks that came in the Kit of Parts as Alan has indicated.

The wiring rules for the power distribution (PD) board state that only one wire may be inserted into the PD connector. But you are allowed to “splice” into power leads from the PD board to feed multiple custom devices like the sensors. This is where the terminal block will come in very handy. Just simply run a red (plus 12 volt) and black (negative) wire from the PD board down to the terminal block. At the terminal block daisy chain the power wires as needed to each of sensor(s). You may also use the terminal block to make the electrical connection from the sensor to the PWM cable.

This would make a nice neat installation, which would be easy to trace and trouble shot.

Re: How should we wire the photoswitchs?
 

Al,

Attached is a graph showing battery voltage logged during a match. This is typical when everything is working correctly. It is worse if there are problems. The horizontal data is in 50 millisecond increments.

I would feel much better if there was some boost in that circuit. Please feel free to give this graph to Kate.

I have looked at a few regulators and most seem to cut off around this same voltage.

We were not using the 24 volt solenoid module. The sensor we had connected was low current, so we were within the current ability of the regulator.

According to the data sheet these line sensors draw 35 ma. With three sensors that will make a total draw of 105 ma. It should be interesting...I suspect it will be an issue. As you said we will just need to wait and see.

-Hugh

Re: How should we wire the photoswitchs?
 

This is to Al S. and Hugh.
Thanks for keeping this idea alive.
In our tests we were using a FRC battery on a test robot. We did not pay any attention to the battery level at the beginning of the tests and immediately after the sensor started to work they blocked the wheels off the ground and started testing how the sensor code effected the drive motors (new loads).

Hugh has shown quite graphically that we may need stabilization. Our IR sensors start to fail at about 10v.
Hugh, do you have any graphs or history of current on that machine ?
What was the measurement point ? (CRIO's output of voltage I'm assuming)

Re: How should we wire the photoswitchs?
 

Hi Charlie,

The voltage is measured at the input to a Jaguar. Attached is the current from the same match. The current data is from the # 2 left motor in our drive train so this only shows one motor. I don't have current for the entire robot. This data is returned on the CAN bus, shipped to the driver station, then logged in a file by the dashboard software.

-Hugh

Re: How should we wire the photoswitchs?
 

Thanks Hugh for the current history.

This seems typical to me and helps me with my current measurement theme with the kids (leading up to current management, I think).

The logical conclusion is that once noise is also taken into account, then we need another entire thread on how to power sensitive devices and which of our existing components are already being taken for granted.

Re: How should we wire the photoswitchs?
 

Hugh,
Your voltage graph is pretty typical of the kind of short duration spikes that occur on the robot. In our experience, the voltage falls actually much lower on occasion. It is not uncommon for it to go down to 4 volts at the input of a speed controller that is pulling a lot of current. It is a good reason to use #10 AWG for drive motors instead of #12 or #14 where the voltage drop across the wire is higher. I will check and see if I can find any data from the manufacturer on how low these sensors actually can operate.

Re: How should we wire the photoswitchs?
 

What gauge wires should we use to connect the sensors to the power distribution board. and does it need to be the white wire or can you use the black and red wires also so i don't use up all of our pwm cables?

Re: How should we wire the photoswitchs?
 

So I worked with the students today to explore the sensor for wiring and sensitivity. Long story short I read this thread prior to attempting any wiring. When we looked at the the voltage at the DSC inputs with a DC volt meter, the sensor appears to sit at ~.7V for logic low and 3.99V for logic high.

Anyone else see this? I honestly don't know if this is expected. With the pull-up built into the DSC I wouldn't have expected so much voltage drop for the high.

At first I assumed we would have to build a circuit for pull-up/pull-down, but after reading the thread about the open collector and DSC built in pull-up I followed the logic. (the data sheet that wasn't too descriptive)

So, does .7 and 4V make sense? Are they within the tolerances for digital high and digital low in the DSC and cRIO? I am assuming if we had been able to sync up with software today they would have just been able to use the VI and be on their merry way. But we probed the values, and then got to thinking. And then that took us on tangents. :)

Thanks!

Re: How should we wire the photoswitchs?
 

Iam,
Those numbers are normal for this device. The switching on the DSC will operate with those levels.